Venturi tube



Dec. 24, 1935. W, s, mEHL 2,025,577

VENTURI TUBE Filed July 18, 1933 4 Sheets-Sheet l f Elvgl., I y l (suc-HON) BYv ATTRNEY WALTER swam. Ely E. INVENTOR W. S. DIEHL Dec. 24, 1935.

VENTURI TUBE Filed July 18, 1933 4 Sheets-Sheet 2 43 45 TRAVEL 1 mum i l I i 5 WALTEES. o/EHL INVENTOR .n TTOR EY Dec.- 2 4, 1935. w. s. DIEHL VENTURI TUBE Filed July 1e, 195s 4 Sheets-Sheet 5 wwf WA LTER 5; o/EHL INVENTOR ATTO R N Y l W. S. DIEHL VENTURI TUBE Filed July 18, 1933 4 Sheets-Sheet 4 88 86 ITRAVEL L4- INVENTOR Patented Dec. 24, 1935' UNITEDv STATES PATENT OFFICE (Granted under the act of March 3, 1883, as

amended April 30, 1928.; 370 0. G. 751) My invention relates broadly to Venturi tubes, and more particularly to controlled Venturi tubes for use with aircraft instruments.

The Venturi tube is most commonly used in aircraft for producing the-suctionrequired for loperating gyroscopic instruments such as the directional gyros, the articial horizon, the turn indicator, etc. It is necessary that the speed of the rotor of each of the said instruments remain evssentially constant in order to obtain the best vper-- formance and to obtain this condition, the operating suction must remain constant. vThe suction obtained from the conventional type of Venturi tube varies with the air speed of the airplane to such an extent that the instruments'are not ellicient and, in some instances, the instruments are rendered inoperative. Itis therefore the primary object of my invention to automatically regulate the amount of suction developed by a venturi so as to obtain the best performance of the instruments operated by suction.

It is another object of my invention to provid in a venturi, means for controlling the suction to a practically constant value above any desired limiting speed.

With the above and other objects in view, this invention consists in the construction, combination and arrangement of parts as will be described more fully hereinafter.-

Reference is to be had to the accompanying drawings forming a part of this specification, in which like reference characters indicating corresponding parts throughout the several views, and in which:

Fig. 1 is a diagrammatic view showing the operation of my improved device against a scale;

Fig. 2 is a side elevation of my improved device shown partly in section;

Fig. 3 is a detail of Fig. 2;

Fig. 4 is a side elevation of a modication of my improved device, shown partly in section;

Fig. 5 is a plan view of Fig. 4 with the outer Venturi shell removed;

Fig. 6 is a view on lines 6-6 of Fig. 4;

Fig. '1 is a side elevation of a modified form of my improved device;

Fig. 8 is the same as Fig. '1 with the outer shell moved aft; l

Fig. 9 is an end view of Fig. 7;

Fig. 10 is a side elevation of another modification of my improved device; i

Fig. 11 is a view on lines ll-11 of Fig. 10.

In order to illustrate the principle involved and the relative positions of my improved device over the conventional type venturi, I have diagrammatically shown in Fig. 1 the outline I0 of an outer Venturi tube with an inner tube or venturi II shown in various dotted positions with reference' to a scale I2 which designates reductions inpressure or suction. The usual location of the inner 5 venturi II is with the exit at or near the throat B and, at this point, the negative pressure has its maximum value. j Thus, for example, at some given speed, the negative pressure at point B due to the outer tube is 8 of mercury. Now, re- 10 tainingthe same speed, if the inner venturi is moved forward so that its exit is at B', the negative pressure due to the outer tube is reduced to 4" instead of 8 of mercury. v4In the same manner, moving the inner tube .I I forward to B" l5 would reduce the pressure due to the outer tube to about 2 of mercury and a similar reduction would take place until the zero point designated as A or the forward'end of the venturi I Il is reached. At the point A the suction developed 20 will be that of the inner tube alone. Referring more particularly to Fig. 2 of the drawings, I3 is a base to which is mounted by standards I4 a double throat type Venturi tube consisting of an outer shell I5 having the con- 25 vverging section I6, diverging section I1 and throat I8, and a concentric small tube I9 having the converging section 20, diverging section 2l and throat 22. v

The converging section I6 s provided with an 30 outer lug 23, an inner lug 24 and a slot 25 over which is mounted an exterior housing 26 that has lever aperture 21. To movably mount the small tube I9 within the converging section I6 of shell l5, I pivotally secure to lug 24 one end of a sup- 35 porting member 28 which has its other end forked and eacn arm 29 of the fork pivotally secured to the forward section 20 of tube I9. A lever 30 having its lower end forked and each arm 3I oi' the fork pivotally secured to section 2| passes 40 through slot 25 and aperture 21 and is pivotaily secured by pin 32 to the housing 26.

A vane 33 is attached by screws 34 to the upper end of lever 30. The movement of lever 30 is limited in forward direction when it abuts against 45 the shell of tube I5 and the motion of the lever in the ait direction is restrained by a suitable spring 35 that has one end fastened to lug 23 and the other end that is threaded as at 36 passing through an aperture in lever 30 and adjust-ably secured 50 by nut 31 screwed onto threads 36.

A flexible hose or tube 3B passes through shell I5 and is connected to a tube nipple 39 that establishes a passage from the throat 22 of small tube I9.- rhe end of the tube as on the outside of I9, being pivotally mounted and attached to the lever, to move forward a proportionate amount.

shell I 5 isvin turn hooked'up or connected with a conveying tube. 40 that connects the instrument to be operated with theventuri.

Thus my vinvention consists in mounting the inner tube I9 so that it may move forward relative to the outer shell I5 whenthe air speed exceeds a fixed, definite value regulated by the resisting' force ofthe spring 35. In the practical operation of mv improved device, the Venturi tube isA suitably mounted on an aircraft by securing the -base I3 to a wing or -other' partfof the plane so that the air stream not only passes through the venturi but` also strikes vane 33. 'When `the airpressure against vanel 33 is sufficient tov overcome the resistance of spring 35, the force of the air striking they vane 'will move lever 39 aft around its pivot point or pin 32 which, in turn, causes tube In this manner, the'relative positions of the inner and outer Venturi tubes are shifted so that the pressure reduction at the throat 22 is controlled and maintained substantially constant'.

Figs. 4 to 6 show a modification of my improved device wherein the inner tube is stationary and the outer tube is movably mounted so that it may move aft relative to the inner tube when the air speed exceeds a' fixed, definite value regulated by the resisting force. In this construction, I provide a base 4I which has a bracket 42, 'integral lugs 43, forward stop members and rear stop members 45. Pivotally secured to lugs 43 by li means of pins 48 and cotter keys 41 are supporting arms 48 whose upper ends have an aperture for pivotally engaging lugs 49 lon outer Venturi tube or shell 50 which consists of a converging section 5I, throat portion 52 and diverging section 53.

To hold the shell 58 so that forward arms 48 bear against stops 44 and to restrain movement of the shell inthe aft direction, I provide a suitable spring 54 that-has one end secured to ar .offset portion 55 of across bar 58 that has itsends positioned in one of a seriesv of apertures v51 in each of the rear arms 48. Ihe other end ofthe spring 54 is secured to an eye bolt 58 that is threaded into a lug 59 extending up from base 4|. The eye bolt 58 is adjustably secured to the lug lby lock washer 60 and nut 6|.'

The bracket 42 extends through a slot 82 in the converging section 5I of tube 50 and mounted' on this bracket inside tube 58 is a small or inner tube 88 that also has a converging section 84, throat portion and diverging section 88.` 'A

' of eye bolt 58 and nut 6|.

tube or conduit 61 having an opening 68 in throat portion 65 passes through the bracket 42 and base 4| and can be suitably connected with 'the instrument to be operated by the venturi.v In

order to obtain high efliciency at low speeds, the slot 82 is covered by a shield 69 that is secured to the bracket 42, thuskeeping the opening or slot 82 closed until the air pressure or resistance 'is completely restrained by spring 54, the rear edge of inner tube 63 is approximately in the throat portion 52 of shell 58. When the air pressure of the airstream passing through the venturi is sufficient to overcome the resistance of spring 54, the force of the air striking the walls of the converging section 5| will tend to move the shell 5 5I) aft through the pivoted arms 48. In this manner the relative position of the outer shell and the inner ntube are shifted so that the pressure.. reduction at the throat 65 is controlled an maintained substantially constant. IO

Figs. 7 to 11 disclose modified forms of movf ably mounting the outer shell of the venturi to the base. In Figs. 7 to 9, the 4shell 18 has four Vlugs 1|, two on each side, and each pair of lugs supports a rod or shaft 12 which in turn movably l5 passes through bearings 13 that are mounted in lugs 14 projecting from base 15. The rods 12 are secured to the lugs1| by pins 18. The motion of vshell 18 is restrained by springs 11 positioned around rods 12 between lugs 14 by means of cups 204 18' and an adjustable nut 19 screwed onto av threaded portion of the rod 12. A shoulder 18| on the rod 12 acts as a stop when the shell is in the normal or rest position. The practical operation of-this form is the same as set out for 25 the modification shown in Figs. `4 to 6; that is, the outer shell isv mounted so that it may move aft relative to the inner tube when the air speed exceeds a fixed definite value regulatedby the resistingforces of springs 11 mounted on rods 30 'I'he amount of resistance can be suitably adjusted by the nuts 19.

In Figs. 10 and 1l, I show a shell 82 having two pairs of side lugs 83 to which are securedby bolts 84 the flanged rollers 85. "-The base 88 has sides 35 lor flanged portions 81 on which the rollers 85 are adapted tohmove, thus movably mounting the shell 82. In order to restrain the movement of the shell, I provide on the underside and preferably in the center, a'pair-of downwardly extend- 40 ing lugs 88 tovwhich is secured by pins 89 a rod 98 that in turn movably passes through lugs 9| projecting .up from the base 88. Positioned on rod 98 between the lugs 9| by means of cups 92 and an adjustable nut 93 is a spring 94 that re- 45 strains the motion of shell 82. In like manner, the practical operation of this' modication .is

' similar to the description .of Figs. 3 to 9. The

outer shell is mounted so that -it may move aft guided by means of rollers rotating on nanges 50 d The herein described invention may be manufactured and used byor for the Government of the llnited States of America vfor governmental purposes, without the payment of anyroyalties 55 thereon.

what relaim isi i l l. In an aircraft suction venturi adapted to be mounted on an airplane in exposed relation to the surrounding air, a base member, an outer tube 70 member, an inner tube member, means movably mounting said inner membercoaxially in said outer member, and means for automaticallymoving said inner member forward with respect to. the outer tube member when external air speed 75 against said last mentioned means exceeds a definite value.

2. In a venturi adapted for use with an aircraft and adapted to be mounted thereon for rapid movement relatively to a surrounding fluid, a base, an outer tube member secured to the base, a second tube member movably secured in said outer tube member, and means responsive to the relative velocity of the fluid surrounding the outer tube constructed and connected to move said second tube member with respect to the outer tube when the air speed of the aircraft exceeds a definite value. Y

3. In a suction venturi for use with an aircraft and adapted. adapted to be mounted thereon in exposed relation to the surrounding air, a base, an outer tube member secured to the base, a second tube member movably and coaxially secured to said first tube member, a suction delivery tube secured to said second tube member, and means responsive to the relative velocity of the air surrounding the outer tube adapted to move said second tube member with respect tothe first-member when a definite value of the air speed of the aircraft is changed.

4. In an aircraft venturi adapted to be mounted on an airplane in exposed relation to the surrounding air, a base, an outer Venturi tube member secured to the base, an inner Venturi tube. member movably and coaxially secured inside said outer member, means responsive tothe relative velocity of the fluid surrounding the outer tube member adapted to move said inner tube member with respect to the outer tube member. to maintain a substantially constant pressure in the throat of the inner tube and adjustable restraining means regulating the movement of said means adapted to move the inner tube member.

, 5. In a suction venturi for aircraft, a base, an outer Venturi tube secured to said base, an inner Venturi tube, means movably mounting said rinner tube in the outer tube, said mounting means having a pivoted shaft extending through the outer tube, a vane secured to the extruding end of said shaft for moving the inner tube when air pressure is placed on vthe vane, and adjustable restraining means adapted to regulate the movement of said shaft'an'd thereby regulate the movement of said inner tube with respect to said outer tube within definite values of air pressure against said vane.- v

6. In a venturi for an aircraft adapted to be mounted thereon in exposed relation to the air,

a base, an inner and outer Venturi tube, means rigidly attaching said inner tube to the base member, means movably mounting said 'outer tube to the base member, means adapted to automatically regulate vthe movement of said movably mounting means when there is relativeV movement of the venturi with respect to the surrounding air where-a by air resistance moversl said outer tube with ree-k spect vto said inner tube when the air speed of the aircraft exceeds a definite value thus maintain-f base, a larger venturi positioned around said small venturi, means slidably mounting .said larger venturi to the base, restraining means for resistingsliding motion of the larger tube until the flow of the surrounding air exceeds a denite to the base and extending through said slot, an

v adapted toV be mounted thereon in exposed relavalue at which point the larger venturi moves with respect to the smaller venturi, and adjusting means for regulating the initial resistance.

8. In a suction venturi for an aircraft and adapted to be mounted thereon in exposed rela- 5 tion to the surrounding air, a base, an outer Venturi tube having a diverging'section, a converging lsection and throatportion, pivoted arms movably securing the outer tube to the base, a slot in said converging section, a bracket secured to the base and extending through the said slot, an' inner venturi mounted on said bracket within the outer Venturi tube, V adjustable means adapted to restrain the movement of said pivoted arms Wherelby said outer venturi moves with respect to said movably securing the outertube tothe base, 'a

slot in said .converging section, a bracket secured -to the base and extending through the slot, an

inner Venturi tube mounted on said bracket Within the outer Venturi tube, a suction tube connected to said inner Venturi tube, means adapted` to restrain the movement of two or more of said arms whereby said outer venturi moves with respect to said inner tube by an amount depending on the excess of air speed of the aircraft over a definite value set by said restraining means, .and means adapted to adjust said restraining means to change the definite value of resistance set thereby. 1

10. In a suction venturi for an aircraft and adapted, to be mounted thereon vin exposed relation to the surrounding air, a base, an outer Venturi tube having a diverging section, a converging section and throat portion, pivoted arms movably securing the outer tube to the base, a. slot in said converging section, a bracket secured inner venturi mounted on saidbracket within the outer Venturi tube, adjustable means adapted to restrain the movement of said pivoted arms whereby said outer venturi moves with respect to said inner Venturi when the air speed ofv the aircraft exceeds a definite amount, a suction delivery conduit connected with said inner venturi, and means secured to said bracket adaptedk to cover the slot in the outer venturi.

11. In a venturi for use with an aircraft and tion to the surrounding air, a base, an outer Venlturi tube having a converging section, a diverging section and a throat portion, a slot in said'converging section, a bracket secured to the base vand extending through said slot, an inner Venturi tube mounted on said'bracket within the outer Venturivtube, a suction tube connected to said inner Venturi tube, andmeans for slidably mounting said outer. venturi to the basewhereby 6,-,`

base lugs having bearings for movably mounting `704 said shaft and means for restraining the move- Y ment of said shaft within predetermined values of a'ir speed of the aircraft.

12.1;1ra. `venturi for use with anaircraft and adaptedto be'mounted thereon in exposed 'rela- 75 '5 bracket secured to the base and extending through said slot, an inner Venturi tube mounted on said bracket within the outer Venturi tube, a suction tube connected to the inner Venturijtube, means. #for movably mounting said outer tube under the influence of air resistance, said means consisting of lugs secured to the underside of thetube and rollers adapted to rotate on said anged sides of the base, secured to said lugs; and adjustable restraining means adapted to control the-movement ot said outer tube within predetermined values of air speed of the aircraft.'

13. In a venturi, an outer Venturi tube, an inner 4 Venturi tube, a suction tube connected to said inner Venturi tube, means mounting said tubes for relative movement with respect to each other and va surroundingfiiuid, and means adapted to be automatically actuated by the uid resistance surrounding the outervtube, thereby regulating the relative movement oi.' said tubes Withrespect to each other to maintain a substantially constant suction in the inner venturi at all uid velocities of the surrounding uid,

WALTER S. DIEHL. 

